The speed of sound and isentropic compressibility of liquid difluoromethane (HFC32) fromT=(248 to 343) K and pressures up to 65 MPa

Abstract This work reports experimental data on the speed of sound in liquid difluoromethane (HFC32, or R32) from T =(248 to 343) K and pressures up to 65 MPa. The results were obtained using a newly-built apparatus, calibrated with toluene over the whole experimental region, and show good agreement with two available data sets. The uncertainties are ±0.01 K in the temperature, ±0.025 MPa in the pressure up to 35 MPa, and ±0.2 MPa above this value. The final uncertainty on the speed of sound is estimated to be ±0.2 per cent. The data were fitted using a simple analytical equation and the results are discussed. The isentropic compressibility was calculated over the ( p , T ) surface where the reported speed of sound values and the corresponding literature densities overlap.